Protector tube



y 1942- w. w. WATROUS, .JR 2,288,861

PROTECTORLTUBE Filed Feb. 27, 1941 "J17. Ilium 7000,17

, I I I I I I 1 lNVENTOR lK/M 74 005, are.

AJwLl wn ATTORNEY Patented July 7, 1942 rao'rnc'roa roar:

. Ward W. Watrous, Jr., East Orange, N. 1., assignor to WestinghouseElectric & Manufacturing Company, East Pittsburgh, Pa., a corporation ofPennsylvania Application February 27, 1941, Serial No. 380,150 Claims.(01. 250-215) My invention relates to tubes and especially to the typeof tube known as a gas-filled protector tube. A

An object of the invention is to provide a simplified protector tubethat is inexpensive to manufacture.

. Another object of the invention is to reduce the erratic operationthat is characteristic of the protector tubes of the prior art.

Still further objects are to properly protect the arc discharge spacebetween the discharge electrodes in a protector tube. v

Other objects and advantages of the invention will be apparent from thefollowing description and drawing in which:

Fig. 1 is a view of a protector tube embodying my invention with certainportions of the casing broken away.

i 2 is a view on lines II--II of Fig. 1.

Fig. 3 is a view on lines III-III of Fig, 1.

Fig. 4 is a modification of the structure of Fig. 1.

Fig. 5 is a view on lines V--V of Fig. 4.

Fig, 6 is a modification of the electrode structure of Fig. 4.

Fig. 7 is a still further modification of Fig. 4.

Fig. 8 is a cross section on lines VIIIVIII of Fig. 7.

Gas-filled protector tubes of the prior art have inherent disadvantageswhich include their high cost. erratic operation, inconvenient mounting,awkward shape, and relatively fragile construction. It is first of allan object of my invention to simplify the construction of .a protectortube and to make one that is both compact and of sturdy construction.Another object of the present invention is to provide a simplifiedstructure which eliminates the erratic operation present in prior arttubes of this type.

In Fig. 1 I have disclosed a preferred embodiment of my invention, whichhas a casing III of glass, preferably of cylindrical shape, with closedends fitting into suitable metal caps II. The cylindrical casing l0 andthe shape of the metal caps ll may be of such a size as to convenientlyfit into the ordinary fuse clip typeof mounting. The two ends 12 of theglass casing may conveniently take the form of a glass reentrant portionl3 terminating in a glass press ll through which are sealed one, andpreferably two, standards or conductors l Sand it of nickel or tungstenwire.

At the center portion of the casing III are two closely spacedelectrodes ll, preferably in the it exactly parallel with one another.These disks have a projecting reduced portion l9 terminating in a flatface to which is attached, as by a screw threaded joint, a stud 2|,preferably of nickel holding a disk or sheet'of thin flexible insulation22 preferably of mica, against the fiat face 20 of the electrode. Thisdisk has preferably a saw-tooth edge 23, illustrated in Figs. 2 and 3.in tight frictional fit against the inner wall of the casing Ill.

The two conductors l5 and I6 sealed through the press have their ends 24bent over and may press against the mica disk'to also help keep thisdisk fiat against the face 20 of the electrode, as illustrated in Fig.3. These conductors are soldered or welded at 25 to a stud 2| preferablyof nickel. The ends of the conductors l5 and ii that extend through thepress H are connected at 26 to the interior of the-cap ll.

It will be noted that this construction is a very economical one becausethe glass portion of the casing, including the cylindrical housing It,the glass ends 12, reentrant portion 13 and press H with the twoconductors extending therethrough, are standard glass lamp forms andmaterials produced by automatic machines. The method of assembling thisglass structure is accordingly familiar to a large body of workers inthe lamp art.

While the two conductors through each press are not absolutelynecessary, yet the double support bearing against the mica disk andwelded to the stud 2| helps maintain the electrode exactly in the placedesired for it. The mica disks help to space the=electrodes exactly onthe axis of the device and help confine the discharge to the surface ofthe electrodes.

In Fig. 4 I have illustrated a still further modification of myinvention in which I have increased the arcing area between theelectrodes and yet have prevented any long path of breakdowntherebetween. It is known, of course, that in the protector tubes of theprior art that the arc may travel to the back surface of the electrodesand fuse the supports and the protective insulation. Where thepossibility exists of a long path breakdown between the electrodes, theglass envelope may craze or crack because of this long arc.

Accordingly, I modify the electrode structure by reducing the diameterof one of the electrodes, such as 30 in Fig. 4, and form a disk ofinsulation 3| as a cover to the other electrode 32 which will enclosethe first electrode 10. This insulaghape of cylindrical disks, withtheir opposed faces tion cover 3| may be of a suitable ceramic material.The smaller electrode 30 has a cylindrical extension 33 extending into ahollowed space 34 enclosing electrode 30. This cylindrical extension 33has central hollow space or depression 35 in turn, into which extends aprojecting portion 36 from the enclosing electrode 32. The result isthat the two electrodes have large interfltting surfaces slightly spacedfrom one another downs, the deviation from the mean voltage breakdown isgreatly lowered.

The enclosed electrode structure of Figs. 4 and 7 makes impossible anybreakdown over a long path thus, preventing erratic operation and damageto the electrode connections.

It is apparent, however, that'many modifications may-be made in the formand arrangement across which the arc discharge may take p ace.

The shape of these interfitting projections may be cylindrical, althoughin Fig. 6 the central projection 36' from the electrode 32 may have aconical formation. This conical projection provides a space ofcontinuously varying distance which permits the discharge to start atthe most favorable spacing for the gas pressure, and then the arctransfers to another region, thus keeping the starting surface fromrapid rosion in operation. The cover 3| may have a suitable vent 31 toprevent any disruptive explosion because of the confined gases. Asuitable support 38 is attached to the electrode 30, and anothersuitable support 39 is attached to the other electrode 32. These may beconnected in'turn to conductors 49 and M sealed through the oppositepresses 42 and 43. The supporting structure .of Fig. 1 could, of course,be utilized with that of Figs. 4, 6 and '7.

The arc discharge may be confined in other ways and the shape of theinterfitting electrodes may also be varied as illustrated in Fig. 7. InFig. '7 the electrode 50' has a hemispherical depression 5| into whichextends a hemispherical projection 52 from the opposite electrode 53with the desired spacing between the two surfaces. The surroundingcircular edge 55 of this hemispherical depression in 5| is placed closerto the adjoining circular face 55 of the electrode 53 than the rest ofthe spacing betweeh the two electrodes. The outside edge 56 and 5'!adjoining these two faces 54 and 55 is reduced in diameter to make asmall chamber 58.

A cylinder of insulation 59, such as alumina or magnesia surrounds thetwo electrodes and maintains the desired spacing between the twoadjacent surfaces of these electrodes. The two electrodes are centeredin the container wall ill by having two mica rings 60 preferably boundbetween the insulation 59 and an exterior flange 6| at each end of theelectrodes. These mica rings 60 preferably have a frictional saw-toothedge 62 bearing against the inner surface of the container wall Ill. Thetube of insulation 59 has a suitable vent 63 to permit gasinterchangebetween the electrode cavity and the bulb space.

In Fig. 7 the spacing and gas pressure can be so proportioned that thearc will start across the spacing between the two annular faces 54 and55. It will then transfer. to the large hemispherical surface of eachelectrode. In this figure the carbon sputtered from the electrodes canonly be deposited on a very limited area of the cylinder 59 opposite thesmall space between the edge 54 of the electrode 50 and the adjacentface 55 of the electrode 53. Because of this limited deposition ofcarbon there will not be a complete leakage path across the insulation59 spacing the two electrodes.

It will be noted that the construction of my'gasfilled protector tubesis simple yet rugged. The. spacing between the two electrodes can bemade very accurately. The electrodes, especially in Figs. 4 and 7, havea large arcing area which decreases erosion and provides a multitude ofpoints in parallel so that in a series of successive breakof mypreferred embodiments, and accordingly I desire only such limitations tobe imposed upon my invention as are necessitated by the spirit and scopeof the following claims.

I claim:

1. A protector tube comprising two closely spaced electrodes havingopposed parallel discharge faces, and having each another face distinctfrom said discharge faces and constituting insulation-attaching faces,an insulating casing surrounding said electrodes, and insulation meansattached to said electrodes with surface arias of said means in tightcoextensive engagement with said insulation-attaching faces andcooperating for both retaining said electrodes spaced from theinsulating casing and for retaining said discharge faces parallel.

2. A protector tube comprising two closely spaced electrodes havingopposed parallel discharge faces, and having each another face distinctfrom said discharge faces and constituting insulation-attaching faces,an insulating casing surrounding said electrodes, and insulation meansattached to said electrodes with surface areas of said means in tightcoextensive engagement with said insulation-attaching faces andcooperating for both retaining said electrodes spaced from theinsulating casing and for retaining said discharge faces parallel andsaid means having-contact at evenly spaced intervals around their entireouter periphery with said insulating casing, and said means beingattached at the center part thereof to said electrode and the saidmeans, electrodes and the said insulating casing being symmetrical abouta common central axis whereby the said means centralizes the electrodeswith respect to the casing and confines the discharge to the electrodes.

3. A protector tube comprising two closely spaced electrodes havingopposed discharge faces,

an insulating casing surrounding said electrodes,

and insulating means in contact with said casing and secured tightly tosaid electrodes to centralize the electrodes and confine the dischargeto the electrodes comprising a complete ring of flexible insulationclamped to parts of said electrodes remote from said discharge faces andin frictional contact at closely spaced intervals throughout theperipheral edge thereof with the interior wall of said container.

4. A protector tube comprising two closely spaced electrodeshavingopposed discharge faces, an insulating casing surrounding saidelectrodes, and insulating means in contact with said casing and saidelectrodes to centralize the electrodes and confine the discharge to theelectrodes comprising a complete ring of mica clamped at a middle partthereof to said electrodes remote from said discharge faces and having acontinuous saw-toothed edge in contact with the inner wall of saidcontainer.

5. A protector tube comprising two closely spaced electrodes, aninsulating casing surround-' ing said electrodes and insulating means incontact with said casing and said electrodes to centralize theelectrodes and confine the discharge to the electrodes, one of saidelectrodes having a projection and the other electrode having a portionenclosing said projection.

6. A protector tube comprising two closely spaced electrodes, aninsulator enclosing the discharge space between said two electrodes,said insulator being also closely spaced to the electrodes at the edgeof the discharge space but attached to said electrodes at a placeremoved from said discharge space whereby sputtered material will notform a leakage path from one electrode to the other across saidinsulator.

7. A protector tube comprising ,two closely spaced electrodes, aninsulator enclosing the discharge space between said two electrodes,said insulator being also closely spaced to the electrodes at the edgeof the discharge space but attached to said electrodes at a placeremoved,

from said discharge space whereby sputtered material will not form aleakage path from one electrode to the other across said insulator, acontainer and insulating means positioning said electrodes within saidcontainer.

- 8. A protector tube comprising two closely spaced electrodes, aninsulator enclosing the discharge space between said two electrodes,said insulator being also closely spaced to the electrodes at the edgeoithe discharge space but attached to said electrodes at a place removedfrom said discharge space whereby sputtered material will not form aleakage path from one electrode to the other across said insulator, acontainer and insulating means positioning said electrodes within saidcontainer comprising a rin mica secured to the attached insulator.-electrodes structure and bearing irictionally against the inner wall orsaid container.

9. A protector tube comprising two closely spaced electrodes, aninsulator enclosing the discharge space between said two electrodes,said insulator being also closely spaced to the electrodes at the edgeof the discharge space but.

attached to said electrodes at a place removed from said discharge spacewhereby sputtered material will not form a leakage path from oneelectrode to the other across said insulator, a container and insulatingmeans positioning said electrodes within said container comprising tworings of mica, each of said rings being secured between said insulatorand one of said electrodes and bearing irictionally against the innerwall of said container.

10. A protector tube comprising two closely spaced electrodes, aninsulator enclosing the discharge space between said two electrodes,said insulator being also closely spaced to the electrodes at the edgeof the discharge space but attached to said electrodes at a placeremoved from said discharge space whereby sputtered material will notform a leakage path from one electrode to the other-across saidinsulator, a depression in the active face of one electrode, and aprojection from the other electrode ex tending into said depression.

11. A protector tube comprising two cylindrical electrodes having theiroutside circular edges closely adjacent and exposed toward each otherand forming a small discharge space therebetween, a cylinder ofinsulation material enclosing the circular edges of saidelectrodes andthedischarge space therebetween and being slightly spaced from saidclosely adjacent circular edges, said cylinder of insulation materialbeing secured to and having extensive surface contact with saidelectrodes at a position remote from said discharge space.

12. A protector tube comprising two cylindrical electrodes having theiroutside circular edges closely adjacent and exposed toward each otherand forming a small discharge space therebetween, a cylinder ofinsulation material enclosing the circular edges of said electrodes andthe discharge space therebetween and being slightly spaced from saidclosely adjacent circular edges, said cylinder of insulation materialbeing secured to said electrodes at a position remote from saiddischarge space, a container and insulating rings attached to saidelectrodes and bearing frictionally against the interior wall of saidcontainer.

13. A protector tube comprising two cylindrical electrodes having theiroutsidecircular edges closely adjacent and exposed toward each other andforming a small discharge space therebetween, a cylinder of insulationmaterial enclosing the circular edges of said electrodes and thedischarge space therebetween and being slightly spaced from said closelyadjacent circular edges, said cylinder of insulation material beingsecured to said electrodes at a position remote from said dischargespace, a container and rings of mica attached to said electrodes andbearing against the interior wall of said container.

14. A protector tube comprising two cylindrical electrodes having theiroutside circular edges closely adjacent forming a small discharge spacetherebetween, a cylinder 0! insulation material enclosing the circularedges of said electrodes and the discharge space and being slightlyspaced from said closely adjacent circular edges, said cylinder ofinsulation material being secured to said electrodes at a positionremote from said discharge space, a depression in the active face of oneelectrode and a projection from the other electrode extending into saiddepression.

15. A protector tube comprising two closely spaced electrodes aligned ona common axis, an insulating cylindrical casing coaxial with andsurrounding said electrodes, and disc-like means transverse to andcentered on said axis and secured at the midparts of said disc-likemeans to said electrodes and said disc-like means making contact at theperipheries thereof with said cylindrical casing, said disc-like meansand cylindrical casing forming a chamber confining the dischargebetweensaid electrodes within said chamber, one of said electrodes having aprojection and the other electrode having a portion enclosing saidprojection for encouraging discharge between said electrodes to occurwithin said enclosing portion.

WARD W. WATROUS, Ja.

